Circle Calculator
Calculate all circle properties from any known value - radius, diameter, circumference, or area with step-by-step solutions.
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Complete Circle Calculator
Calculate any circle property from a single known value. Enter radius, diameter, circumference, or area to instantly get all other measurements with step-by-step calculations.
Circle Formulas
A circle is a perfectly round shape where every point on its boundary is equidistant from the center. The key formulas are: Area = πr², Circumference = 2πr, and Diameter = 2r. Pi (π) is approximately 3.14159.
Circle Area Formula
A = πr²How to Use This Calculator
Circle Calculator Applications
Construction
Calculate circular foundations, pipes, and architectural elements.
Landscaping
Design circular gardens, ponds, and pathways.
Engineering
Design wheels, gears, and cylindrical components.
Education
Learn circle geometry with visual explanations.
Frequently Asked Questions
The diameter is exactly twice the radius (d = 2r). Conversely, the radius is half the diameter (r = d/2). The diameter is the longest chord that passes through the center of the circle.